[ubuntu] Set up a mixed Ubuntu/Windows home network?

http://ubuntuforums.org –
I have 4 computers- 2 desktops running 10.04
1 laptop running 10.04
1 desktop with Windows XP.
I have been googling now for a few hours. So far, I have Samba set up so that windows sees one of my ubuntu desktops. None of my other Ubuntu PCs can access the shared folder, only XP. Is there any way I can share a folder from one Ubuntu desktop, and be able to access it from all my other PCs (both ubuntu and WinXP)? Or is there a way I can share a folder on the Windows PC and be able to access it from all others? I'm pretty new at this.
Any suggestions are greatly appreciated.
(HowTos)